(c)
[image:8_image38.jpeg]
The required area
$= 2 \times \int_{0}^{4}\sqrt{4 - x}\ dx$
$= {2\left\lbrack \frac{(4 - x)^{3/2}}{3/2} \right\rbrack}_{0}^{4} = 2\left\lbrack - \frac{2}{3} \times 0 + \frac{2}{3}{(4)}^{3/2} \right\rbrack$
$= \frac{32}{2}\ sq\ units$